Thinking about a Bus/RV

[Ted]

OK. Juggling those components, the obvious answer is turbo V8 in the RX7.

I’d had that thought. It would split the block in half, but I’d had the thought.

If I blow up the 12A in the RX7 I’m thinking a Renesis engine is a better solution. 100 lbs lighter and 100 HP more.

 

[Ted]

I'd planned on putting the new turbo on the bus today, only to find that Cat had left out a few parts that I needed, so that was short lived. But I did get the new turbo clocked to the correct position so that the compressor, turbine, and oil inlet/outlet are all facing the proper directions.

Then I went to go add the water pressure tank/accumulator I'd bought since I'd gotten foiled in putting the exhaust manifold and turbo on, only to find that I had bought the wrong size fitting. Grr.

So then I decided to attach the fuel cooler that I'm adding (this was originally the oil cooler I'd put on the RX-7 that was undersized and the hoses blew, but it will do just fine in a low pressure return application). I attached that to the brackets for the transmission coolers, and so now I just need a couple of couplings and some hose and clamps to hook that up.

I then did another couple of tweaks. I replaced the thermostats (190F stock) with 180F stats. The reason for this is to try to get more coolant flowing through the radiator before the electric fans start to kick on. In a normal front radiator setup, there's a lot of excess airflow just going down the road. With a rear radiator bus there's not as much of that, and the fans end up having to force some amount through. Since these thermostats take something on the order of 10-20F to open fully (I've heard different numbers), that results in full coolant flow at a lower temperature. Essentially, a normal front radiator setup has full airflow and then adds coolant flow. Mine is more the reverse - get full coolant flow, and then add the air.

I also added the Amsoil Dominator Coolant Additive that @jesse was insistent will lower my coolant temperatures. So far it's working - the engine was showing 60F coolant temp! Oh, wait, it hasn't run since November.

 

[Ted]

I put a video together of the turbo and exhaust removal:

 

[Ted]

One thing that's been the case on the bus for a while, but that now I think I want to address, is the motor mounts. The stock motor mounts are just rubber pucks with bolts through them. The rubber has shrunk/degraded over time and now the bottom pucks will rotate. This lets the engine shift around quite a bit, especially when going from D to R (and thus the transmission output shaft changing load direction).

Because of the simple construction, it looks simple enough to get polyurethane pucks to replace them. I've sent out for a quote, figuring on 70A durometer level. I couldn't find much for good references on what durometer I should target, and the main thing I've gotten from it is that it depends heavily on the engine you're running. Given that this is a decent sized straight 6 diesel (and thus has strong power pulses), I don't want to get too hard on the mounts. 70A seems like a good place to start and I could look at changing them out if it ends up being too hard.

Another thing I've been looking at is replacing the stock rooftop heat pumps with mini splits. This is commonly done in bus conversions, skoolies, etc., but you see it less often on normal RVs. The rooftop air units are really junk. They're inefficient (and have no standards for efficiency - they don't even have to publish SEER or EER), loud, not super reliable, and the heat pumps quit working around 25F.

I need to think on this more, as there really isn't a good bolt-in setup. The ceiling cassette units that household mini splits use are 24" x 24", which is roughly 6-9" bigger in length and width than the stock ceiling units. Your standard wall mount mini split indoor unit wouldn't work in my RV as literally every higher portion on the wall is covered in cabinets, and we do use them all.

The outdoor units I think are actually easier to handle, albeit requiring some significant modifications. Behind the rear closet in the bedroom there is actually a significant amount of wasted space. If I cut a big hole in the back wall of the RV and then made mounts accordingly, I could mount the outdoor units there. Then cover it up with louvers, similar to either the engine door or like what you find on a "newer" MCI bus:

That's a really big project though, and may end up being something that I not do on this bus.

 

[ElPaso Pilot]

One thing that's been the case on the bus for a while, but that now I think I want to address, is the motor mounts. The stock motor mounts are just rubber pucks with bolts through them. The rubber has shrunk/degraded over time and now the bottom pucks will rotate. This lets the engine shift around quite a bit, especially when going from D to R (and thus the transmission output shaft changing load direction).

Because of the simple construction, it looks simple enough to get polyurethane pucks to replace them. I've sent out for a quote, figuring on 70A durometer level. I couldn't find much for good references on what durometer I should target, and the main thing I've gotten from it is that it depends heavily on the engine you're running. Given that this is a decent sized straight 6 diesel (and thus has strong power pulses), I don't want to get too hard on the mounts. 70A seems like a good place to start and I could look at changing them out if it ends up being too hard.

Another thing I've been looking at is replacing the stock rooftop heat pumps with mini splits. This is commonly done in bus conversions, skoolies, etc., but you see it less often on normal RVs. The rooftop air units are really junk. They're inefficient (and have no standards for efficiency - they don't even have to publish SEER or EER), loud, not super reliable, and the heat pumps quit working around 25F.

I need to think on this more, as there really isn't a good bolt-in setup. The ceiling cassette units that household mini splits use are 24" x 24", which is roughly 6-9" bigger in length and width than the stock ceiling units. Your standard wall mount mini split indoor unit wouldn't work in my RV as literally every higher portion on the wall is covered in cabinets, and we do use them all.

The outdoor units I think are actually easier to handle, albeit requiring some significant modifications. Behind the rear closet in the bedroom there is actually a significant amount of wasted space. If I cut a big hole in the back wall of the RV and then made mounts accordingly, I could mount the outdoor units there. Then cover it up with louvers, similar to either the engine door or like what you find on a "newer" MCI bus:

That's a really big project though, and may end up being something that I not do on this bus.

There is another advantage to placing the units in the back closet...

 

[Ted]

There is another advantage to placing the units in the back closet...

This is one of the reasons why I've both measured the total height of my bus, and also have a Garmin RV GPS that includes the height and helps to alert me to bridges/overpasses ahead that may prove problematic.

 

[Ted]

I did a video comparing the old and new turbos. I know it's blasphemy to say, but the 25+ year old turbo design that came on my Caterpillar engine does, in fact, have room for improvement with modern technology.

 

[NealRomeoGolf]

I did a video comparing the old and new turbos. I know it's blasphemy to say, but the 25+ year old turbo design that came on my Caterpillar engine does, in fact, have room for improvement with modern technology.

I won't tell the turbo group.


They'd agree though.

 

[charheep]

Maybe that old turbo will fit on one of the bikes...

 

[Ted]

I won't tell the turbo group.


They'd agree though.

Yeah, OEM turbos are always a compromise of some sort on cost and "good enough to meet the requirements."

On my bus, cost is less of a factor, and "meeting Ted requirements" (i.e. making it better than it was out of the box) is a much higher priority.

There's a really good Caterpillar group on Facebook that I'm on. Not surprisingly, most of the content is around C15s since those are the most popular in big truck engines and popular for hopping up. But there's also some really good 3126 folks. Lot of interest in how this turbo works out. One person noted that he knew someone who put a bigger turbo on a 3126 and it had way too much turbo lag, but not sure how big that person went, and it was with a manual transmission. With an automatic the turbo lag is essentially a transient (especially off idle) and once you've got the boost going, you should be good. I'm really not anticipating an issue - this turbo had basically zero lag off idle (and only even a little tiny bit of lag up at altitude) so I think it'll be fine.

Maybe that old turbo will fit on one of the bikes...

I'm not going to trash the old turbo for sure. It's really not in bad shape overall, it looks worse than it is. It's definitely too big for the bikes, and at this point I really don't own anything it's worth putting on. I'll figure something out.

 

[Albany Tom]

That's pretty cool, really. Maybe "things get worse" doesn't apply universally, except for software and consumer products.

 

[Ted]

That's pretty cool, really. Maybe "things get worse" doesn't apply universally, except for software and consumer products.

The ability to do things better continues to increase with time.

The reality of things being done better depends on a number of factors, including what consumers are willing to pay and what they're willing to tolerate, and what companies are forced to do by regulations.

 

[NealRomeoGolf]

The ability to do things better continues to increase with time.

The reality of things being done better depends on a number of factors, including what consumers are willing to pay and what they're willing to tolerate, and what companies are forced to do by regulations.

Biggest driver is competition. As much as I hate Cummins, they push us to be better.

 

[Ted]

Biggest driver is competition. As much as I hate Cummins, they push us to be better.

Definitely agree overall. On the other side sometimes there's a lot of cheap junk out there when the competition is more over price than quality, but the fact that I can now buy a $33 oscilloscope off Amazon (not a super functional one, but just the fact that it exists and does all I need relative to the C4.4 swap) is pretty incredible.

 

[Ted]

Managed to get the manifold and turbo back on last night. That wasn't particularly fun, but it's in. Now to work on details of installation. $23 for a new boost elbow with clamps off Amazon since the old one is now the wrong size.

 

[Ted]

I've been doing some more thinking about a couple of detail projects and think I have some plans in place.

I found and ordered some polyurethane stock. Now we'll see when it ships. That will be used for making the new motor mounts. That should help keep the engine both more in place and keep vibrations more how they should be.

I also spent some time looking at the generator, and I think I've figured out a way to make it quieter and vibrate less. This mostly involves copying what the $2M RVs do - a separate airbag suspension for the generator with little tiny airbags which are specifically designed to absorb vibrations, not just support the weight, like this:



I'm going to try to get some of these coming, but essentially the design will be having a tray underneath the generator that will support the generator and disconnecting it from the standard mounts on the bus.

With this additional tray, I can/will also attach material that's sound deadening (similar to what you have on a lot of modern cars) with some carefully placed baffle material to keep the airflow in/out of the generator directed properly.

Lastly, I also found that the floor of the RV directly above the generator is essentially a big piece of sheetmetal which very much rattles like a tin can when you tap it. There's room to add some sound deadening material there, which I will do.

How many of these I get done before the next trip, that part I can't say for sure. But I think I've got some ideas in place that I can use. The generator sound on this RV has always been extremely annoying to me. While I won't get it silent like some of the new high end ones do (they go to the extra length of a generator bay that's sealed), but I think I can make some good progress towards quieting it.

 

[charheep]

Great ideas

 

[Ted]

Great ideas

I think when you look at the difference between cheap RVs and expensive RVs, the real difference comes down to those details that get noticed an executed upon. So, I'm just trying to execute those details that the manufacturer missed.

 

[CJones]

Might be worth looking at spray-on sound deadening stuff like Lizard Skin. I've been tempted to try it on the Jeep, but haven't pulled the trigger yet. Let me know how it goes.

 

[MIFlyer]

I've been doing some more thinking about a couple of detail projects and think I have some plans in place.

I found and ordered some polyurethane stock. Now we'll see when it ships. That will be used for making the new motor mounts. That should help keep the engine both more in place and keep vibrations more how they should be.

I also spent some time looking at the generator, and I think I've figured out a way to make it quieter and vibrate less. This mostly involves copying what the $2M RVs do - a separate airbag suspension for the generator with little tiny airbags which are specifically designed to absorb vibrations, not just support the weight, like this:

View attachment 114504

I'm going to try to get some of these coming, but essentially the design will be having a tray underneath the generator that will support the generator and disconnecting it from the standard mounts on the bus.

With this additional tray, I can/will also attach material that's sound deadening (similar to what you have on a lot of modern cars) with some carefully placed baffle material to keep the airflow in/out of the generator directed properly.

Lastly, I also found that the floor of the RV directly above the generator is essentially a big piece of sheetmetal which very much rattles like a tin can when you tap it. There's room to add some sound deadening material there, which I will do.

How many of these I get done before the next trip, that part I can't say for sure. But I think I've got some ideas in place that I can use. The generator sound on this RV has always been extremely annoying to me. While I won't get it silent like some of the new high end ones do (they go to the extra length of a generator bay that's sealed), but I think I can make some good progress towards quieting it.

In the lab, we'd just let it float in a pan of mercury. it works great for absorbing vibrations

 

[MIFlyer]

Might be worth looking at spray-on sound deadening stuff like Lizard Skin. I've been tempted to try it on the Jeep, but haven't pulled the trigger yet. Let me know how it goes.

yes, and the peel and stick asphalt stuff. on my truck I used both and it helped

 

[Ted]

Might be worth looking at spray-on sound deadening stuff like Lizard Skin. I've been tempted to try it on the Jeep, but haven't pulled the trigger yet. Let me know how it goes.

I thought about that as well, but I think the standard dynamat style is what I’d rather go with.

The big question I have is whether I can get the surface good enough to have the stuff stick with the generator in place. Not sure on that one.

 

[SoonerAviator]

I thought about that as well, but I think the standard dynamat style is what I’d rather go with.

The big question I have is whether I can get the surface good enough to have the stuff stick with the generator in place. Not sure on that one.

I bought some Kilmat that seems to hold up pretty well on the underside of the trunk in the Caddy. Adhesive-backed butyl rubber.

 

[Ted]

I bought some Kilmat that seems to hold up pretty well on the underside of the trunk in the Caddy. Adhesive-backed butyl rubber.

I've been using Rockmat - used that on my semi truck and have also been putting it on the Cobra. Haven't tried the Kilmat or heard of it before - maybe I should look for some comparisons.

 

[SoonerAviator]

I've been using Rockmat - used that on my semi truck and have also been putting it on the Cobra. Haven't tried the Kilmat or heard of it before - maybe I should look for some comparisons.

Probably six of one/half dozen of the other.

 

[Ted]

Probably six of one/half dozen of the other.

Kinda what I was thinking.

I'll see what I have time for over the weekend and work on projects accordingly.

 

[Ted]

The turbo is fully bolted up. My local hose shop made up a perfect hose to provide the oil supply, and I got the center section clocked properly so that the turbo drain bolted back up to the block perfectly. It's nice that all of the dimensions really keep this essentially a bolt-on, with the compressor being the only part enough bigger to notice.

I managed to do a start and a leak check, which passed successfully. No oil leaks, no fuel leaks from my fuel cooler on the return line. I let the bus air up fully and did a DOT air leak check and it passed that, too. It'll bleed all of the air out after a couple of days of sitting, but overall the system is pretty tight which I'm happy about. Went through and greased up all the zerks as well as I work towards getting the bus ready for the season.

Unfortunately I couldn't do a test drive as the wastegate actuator that they sent with the turbo didn't fit. The issue is that it interferes with the drain tube, because the factory Cat one is on a 3/4" longer bracket. Cat doesn't sell the wastegate actuator separately, they only sell the turbo (so sayeth the dealer), so then I called back the place I bought the turbo from, and they're going to send me a different actuator. Between the one they sent me with the turbo originally, the old one from the old turbo, and what they send me next, I should be able to get it back on and then drive it.

I was hoping that the polyurethane for making my new motor mounts would arrive by now, but it hasn't shown up yet. The first of the mini airbags for the generator mount should show up today (with the rest coming later this week) so I can work on how I want to mount them. I did figure out where I want to tap into the air system to get air supplied for this as well. So hopefully I can get that whole setup welded up, plumbed, and installed.

Admittedly every time I crawl under the bus and see how far below my standards this RV is as far as overall construction (1/8" square tube everywhere that's only welded on 1 or 2 sides at most, hideous designs like the generator mount, things like that) it does get me searching for Prevosts. Maybe an economic downturn will bring up some opportunities.

 

[Ted]

Oh - and for the record - my biggest hangup on a Prevost is that the best engine I can get in it is a Detroit Series 60. Unless I want to buy one of the Cat repower engines, which might be too much work even for me. The Series 60 is a good enough engine and known for its good fuel economy, but I really like having a Cat.

Funny enough, in RVs of this era, the 3126/C7 was considered the "low end" engine, with the Cummins 8.3, even if it had the same horsepower, being the higher end model. There were some with 5.9 Cummins which has a lot of potential. I see a few people in the RV forum with C9s on up, but that market just wasn't big in the RV world, and Cummins really does own it these days.

 

[TCABM]

…my biggest hangup on a Prevost …

Not to pick nits here, but do you have enough of Prevost knowledge/experience base to know you’ll the satisfied with the engineering & build quality?

 

[Ted]

Not to pick nits here, but do you have enough of Prevost knowledge/experience base to know you’ll the satisfied with the engineering & build quality?

Good question, especially given my standards and propensity to overengineer things to the nth degree. I think the truthful answer is "I read it on the internet so it must be true" with some combination of "I'll always find something wrong".

The big thing with the Prevost (or other bus conversions) is that you're taking a bus designed for commercial use that has to last 1M+ miles, and that's not just the chassis, but also the interior of the bus. When the RV manufacturers buy a Freightliner XC chassis, this is what they get:



It is perfectly doable to build a good body-on-frame setup with this. The problem is that most of the companies just don't do it. If my RV was built with the 1/8" square tubing being welded on all 4 sides instead of just 1, I bet it would make a hugely noticeable difference. And if it was built out of thicker, stronger metal, that would help further.

When a "green" (to use airplane terms) Prevost shows up for its conversion, it looks like a bus, because it's a bus. I think Prevost even does the slides in-house. The unibody construction has a number of benefits (although some negatives). I've never driven a Prevost, but I've been a passenger in them for commercial busses. The overall ride quality and feeling of build quality is immediately apparent going down any sort of road, especially compared to my RV (which, to be fair, is actually a lot better than some of the lower end ones - I'd call this middle of the road). People refer to the ride as Rolls Royce like, and it's definitely a lot closer to that than my RV, which is fine so long as you're on a good road.

Keep in mind mine is not the worst by any means and I see a lot of people with worse complaints about build quality on newer RVs of a similar class. When I see what some people have, especially in the travel trailer realm, it's noticeably worse. My roof is actually aluminum over wood with some sort of steel/aluminum frame up there, significantly improved from those who just have vinyl over plywood.

If I were to really do what I wanted, I'd probably do a body on frame setup, and do it mostly from scratch. It would weigh a lot, but it would be well built. With the kids at the ages they are and the list of projects I have going on, I'll just complain about this one more unless something better falls in my lap.

 

[Ted]

While randomly Googling, I found a video where Marathon has a couple of "green" Prevosts come in for conversion, so able to see it without the interior. I was mostly looking for the difference between the X3 vs. the H3 (their two variants). The structure is really what I was interested in - and exactly what I was mentioning above. Stainless steel square tubing welded on all 4 sides instead of the standard raw steel (by itself ok) welded on 1 or 2 sides.

Mostly I like the X3 more than the H3 because the driver is on the same level as the rest of the bus (one of my favorite parts about our RV) but the benefit of the H3 with the driver's area being lower is that gives enough headroom for a bunk bed above.

 

[Ted]

Polyurethane for the engine mounts and air springs for the generator mount arrived.

 

[Ted]

Finally did a short video on the AirTabs I installed over a year ago. TL;DR summary: They work and I'm happy with them.

 

[Ted]

YouTube is funny. This AirTabs video (posted 6 hours ago) has the most total views of 12 out of my last 13 videos, and of the past 10 videos is #1 at this point since publishing by an order of magnitude.

And here I thought this video wasn't very good.

 

[NealRomeoGolf]

I posted a hand flown RNAV approach and got 700% more views in the 1st week than any of my others. I guess sometimes the algorithm picks certain things up.

 

[Everskyward]

I guess sometimes the algorithm picks certain things up.

Off topic, but I can't explain this...

I posted a number of videos of villages in West Papua that I visited on a trip. These are the views for one of them. I didn't promote them in any way. There is no commentary or explanation, just the name of the villages. The views keep going up, and so do subscribers. I got a little weird about this and changed my account name to something other than my real name, but the views keep coming.

 

[Ted]

Off topic, but I can't explain this...

I posted a number of videos of villages in West Papua that I visited on a trip. These are the views for one of them. I didn't promote them in any way. There is no commentary or explanation, just the name of the villages. The views keep going up, and so do subscribers. I got a little weird about this and changed my account name to something other than my real name, but the views keep coming.

View attachment 114965

I really don't understand some of it. If I look at my "popular" videos (YouTube lists 12) that have 3.3k views up to 25k views, most of them I don't see as being ones that make a ton of sense to get that much attention.

That number of views (and getting associated subscribers) is an interesting one.

I'm tracking my stats more closely as I'm trying to get towards monetization on my channel. Not because I expect to make any money off of it worth noting (and realistically probably more of a headache for my accountant to throw it on my tax return), but more just as a goal to achieve. The one area I'm still short is the requirement of having 4,000 watched hours in the past 365 days. Currently I'm just over 3700, but at the beginning of the year when I started looking at it more I was at around 3550. Since it's cumulative, to increase you have to have more hours watched than were watched a year ago the same day. I've been trying to post a video and a short every week and that's been working.

The whole thing can get fairly interesting to watch (at least for a numbers person). Given that today's video has been watched 31 hours today (and increasing), tomorrow's cumulative hours should be noticeably higher than today's.

Incidentally, I agree with changing the YouTube channel from your real name. I did that to my channel a couple years ago, although I remain a pretty easy person to find all things considered. More than anything I think having a "Channel Name" as opposed to a person's name gets the point of the channel across more.

 

[Ted]

I've been able to spend some time working on the new generator mount, or at least starting on it. I got the original "mount" (if you want to call it that) off and the more I dug into it, the worse it was. What complete garbage. If this doesn't quiet things down, I'll be shocked. Nothing was welded fully or on more than one side. The generator itself was providing all of the rigidity in the mount, and once removed it was extremely flimsy. This isn't a good combination.

I've thought about the new mount some and I think I've figured out what is going to be the best way to go about it that should both maximize rigidity and also make the generator serviceable (which it really wasn't before, outside of oil changes). So, next will be cutting and welding up some metal.

 

[Ted]

Spent my shop time today working on the motor mounts for the engine. I knew I wasn't going to finish up the generator mounts, and figured that this was a better idea.

Fabrication is slow. I always underestimate how slow it's going to be. Even though nothing I'm doing is complicated, just thinking about how you want to do it takes time, plus I'm learning how to best use some of my tools. I can say I've figured out how to use my band saw to cut polyurethane very well now, it's cutting perfectly square and giving a very nice surface finish.

The front and rear mounts of the bus are completely different. The front mounts are in the center front of the engine (which is the very back of the bus, being a diesel pusher). I thought those would be harder because of access, but in the end they were much easier. I finished them first. I ended up making 3-piece bushings, with top and bottom pucks and a middle puck that went through the frame on the motor mount, with the stock sleeve going through the middle.



The rear mounts (further forward) end up having a very small lip where the weight gets supported by the frame side motor mount. The stock mount has an interesting design to make up for this, but it's not going to work for me. The stock setup is also sandwiched together by big 1/4" thick steel washers on either side. What I'm going to do is make two more of these and essentially sandwich the top and bottom 4" diameter pieces of poly between those, and then still have a center piece of poly as well. The inside spacers will serve to just distribute the load better, and I'll hog out their ID a bit so that they don't end up touching the bolt and spacer going through. This probably doesn't make sense in the description, but it will make more sense once I do it.

Unfortunately (and as expected) I need more supplies to finish that. But, I can keep on moving forward with both projects until I head to the metal supply store next week.

 

[Ted]

The next video on the turbo and exhaust manifold install: